I think they're saying that the investment in peak capacity may be already made, whereas the returns on use are ongoing, so creating incentives to save electricity may not be valuable to the companies.
Don't know if that's their actual cost-structure, but it's plausible in the abstract.
Electric utilities require capital investment proportional to peak usage, but only earn returns on average usage. This will only increase the ROIC of an electric utility by reducing the peak:average ratio.
Additionally, electric utilities are in a constant cycle of capacity upgrades to keep up with increasing demand. Customers adding distributed storage allows utilities to delay capital investment (which makes the company look better in the near-term).